This invention relates to a horizontally oriented mold closing unit for an injection molding machine and is of the type which has an automatic mold exchanging device as well as an associated injection mold assembly having a mold body composed of standardized plates. The mold body is, on the clamping sides, bounded by respective back plates which project beyond at least one end face of the mold body. The mold closing unit further has coupling members at the underside of the injection mold assembly as well as a mold exchanging table which is shiftable in the mold closing direction in guides to both sides of the lateral prolongation of the mold clamping space of the die closing unit throughout a displacement path which corresponds at least to the height of one mold. The injection mold assembly is moved on a conveying track into the mold clamping space from the mold exchanging table with the aid of an endless conveyor chain engaging the injection mold assembly from below by means of the coupling means.
In a die closing unit of the above-outlined known type, as disclosed, for example, in German Pat. No. 3,242,169, to which corresponds U.S. Pat. No. 4,462,783, the injection mold assembly is connectable to the conveyor chain by a coupling bar movably supported in the conveying track. The conveyor chain is, in the zone between the mold clamping space of the die closing unit and the mold exchanging table, disposed in a horizontal plane, that is, its end sprockets have a vertical axis. During the coupling step, the carrier members of the conveyor chain slide, in the zones of chain reversal, laterally into a corresponding horizontal transverse groove of the coupling bar. The coupling bar is, in turn, provided with carrier pins for establishing coupling with the injection mold assembly. The carrier pins project, from below, into corresponding bores provided in the mold body. The gliding support for the coupling bar is situated necessarily in the zone of the clamping space which is disadvantageous in that access to the clamping space is significantly limited.
It is further known to provide injection mold assemblies with back plates which project beyond the quadratic mold body at both end faces thereof. Such an arrangement is disclosed, for example, in German Offenlegungsschrift (Non-Examined Published Patent Application) No. 2,332,205 and European Patent Application No. 92,686. These prior art constructions, however, serve other purposes; they provide for example, the injection mold assembly with coolant and power.